Cons:

One thing you can say about the team at Valve Software: they don't like to rush. After taking six years to craft the sequel to Half-Life, it's taken another eighteen months for the first mini-expansion, Half-Life 2: Episode One, to arrive. As the initial installment of a trilogy to be offered in episodic format, the good news is that Episode One is a welcome return to the world of Half-Life 2, with the same great graphics and gameplay that helped that game win numerous awards in late 2004 (including GameSpy's PC Game of the Year).

Episode One starts off exactly where Half-Life 2 ended: with you (as scientist/killing machine Gordon Freeman) atop an exploding Citadel, with your sidekick, the spunky Alyx Vance, about to be toast. Without spoiling things, let's just say that Alyx is kept out of harm's way, and the two of you are quickly reunited outside at the base of a smoking Citadel. After establishing an uplink with old friends Dr. Kleiner and Alyx's father Eli (once again voiced by Robert Guillaume), you discover the Citadel is about to go kerplooey, and in order to give yourself, Alyx and countless other citizens more time to escape City 17, you'll have to go back in to try and delay the meltdown.

There's a good deal of exposition at the start of Episode One, as characters are quickly reintroduced and tasks are laid out before you. The intro includes a reappearance by Dog (Alyx's pet robot), who makes your re-entry into the Citadel a memorable one. Once inside, you and Alyx spend a lot of time exploring the deteriorating monolith, giving you a chance to get reacquainted with the gravity gun. Before long, you'll be flinging around Combine soldiers just like the good ol' days. As you work your way to the Citadel's central reactor core, you're confronted with a healthy dose of puzzles, which start out simple enough but require more imagination to solve as you proceed.

Alyx Vance returns for Episode One, and remains by Gordon's side for most of the game.

Once you've delayed the Citadel meltdown (and picked up some extra intel on what the Combine is up to in the process), the second half of Episode One focuses on Gordon and Alyx's efforts to haul ass out of City 17. Of course, the escape is anything but simple, as you're first forced underground where you have to deal with headcrabs, zombies, and ant lions, and then you make your way onto the streets where you get knee-deep in combat with Combine soldiers, who are none too happy with the information you pilfered from the Citadel.

The gameplay in Episode One never strays too far from the familiar Half-Life formula: levels are kept pretty linear as you're steered from one challenge to the next, with lots of scripted events to move the plot along. The opening levels in the Citadel feel the most unique, due to the heavy emphasis on storytelling, the gravity gun, and all the puzzles involved with stabilizing the reactor. Things slow down a bit once you go underground and start fighting zombies, although there are a few interesting scenes where you have to shine your flashlight on enemies so Alyx can see and shoot them in the dark. Once you get outside with a full complement of weapons, things move along much faster, although it can sometimes feel a little too familiar, as if you're replaying the later sections of Half-Life 2 instead of new content.